Compositions comprising boron compounds and polyphenyl thioethers

ABSTRACT

Compositions comprising polyphenyl thioethers, polyphenylethers - thioethers or mixtures thereof and a triphenylborine exhibit improved corrosiveness toward copper and silver without loss of oxidative stability. Such compositions are useful as functional fluids.

United States Patent [191 Clark et al.

[451 Aug. 28, 1973 COMPOSlTlONS COMPRISING BORON COMPOUNDS AND POLYPHENYL THIOETHERS [75] Inventors: Frank S. Clark; Loren W. Bannister,

both of St. Louis, Mo.

[73] Assignee: Monsanto Company, St. Louis, Mo.

22 Filed: July 29, 1971 [21] Appl. No.: 167,465

[52] US. Cl 252/78, 252/46.3, 252/49.6, 252/389 A, 260/6065 B [51] Int. Cl C09k 3/00 [58] Field of Search 252/75, 78, 389, 252/49.6, 46.3; 260/6065 B {56] 7 References Cited UNITED STATES PATENTS 2,312,208 2/1943 Clayton et a1. 252/75 Primary Examiner-Leon D. Rosdol Assistant Examiner-l-latris A. Pitlick A ttorney-Robert E. Wexler, Neal E. Willis et a1.

[57] ABSTRACT Compositions comprising polyphenyl thioethers, polyphenylethers thioethers or mixtures thereof and a triphenylborine exhibit improved corrosiveness toward copper and silver without loss of oxidative stability. Such compositions are useful as functional fluids.

12 Claims, No Drawings This invention relates to compositions comprising polyphenyl thioethers, polyphenyl ethers-thioethers or mixtures thereof, containing from three to eight aromatic groups and a corrosion inhibiting amount of a triphenylborine. The compositions of this invention are useful as functional fluids.

Polyphenyl thioethers and polyphenyl etherthioether combinations have found wide application as functional fluids due to their excellent thermal stability and lubricity. For example they have been found to be valuable as hydraulic fluids and as lubricants in motor operation, particularly in jet engines, and as heat trans fer agents. Two of the most rigorous demands on fluids are made by jet aircraft hydraulic systems and jet en gine lubrication systems. For example, as the speed and altitude of operation of jet powered aircraft increases, lubrication problems also increase because of higher operating temperatures and higher bearing pressures resulting from the increased thrust needed to obtain higher speeds and altitudes. Thus, the service conditions encountered by functional fluids become increasingly severe, and therefore, the useful life of such fluids is shortened.

The useful life of any lubricant or hydraulic fluid can be adjudged on the basis of many criteria such as the extent of viscosity increase, the extent of corrosion to metal surfaces in contact with the lubricant and the extent of engine deposits. Those skilled in the art have found various ways to improve lubricants and to thus retard or prevent the efi'ects which shorten the useful life of a lubricant. Thus, for example, small amounts of other materials, or additives, can be added to lubricants in order to affect one or more of the properties of the base lubricant. However, it is difiicult, especially as operating temperatures are increased, to find additives which will still perform the function for which they are added and yet not inject other problems.

Therefore, an object of this invention is to extend the useful life of polyphenyl thioethers, polyphenyl etherthioethers or mixtures thereof by reducing their corro-. sivity toward certain metals without adversely affecting oxidative stability of the ethers.

These and other objects will become evident upon consideration of the following specification and examples.

The above and other object of this invention are car-v ried out by admixing polyphenyl thioethers, polyphenyl ether-thioethers or mixtures thereof with a corrosion inhibiting amount of a triphenylborine. The etherboron compositions of this invention exhibit reduced corrosiveness toward metals without an adverse efiect on oxidative stability of the base ether and thus have an extended service life even under the severe conditions encountered in jet engines and other devices operating at temperatures of the order of 600F. The composi-, tions exhibit markedly reduced corrosion toward copper and silver.

The improved compositions of this invention comprise a major amount of an ether base fluid of the formula wherein R is phenyl, alkyl-substituted phenyl wherein the alkyl is of not more than 4 earbon atoms, alkoxysubstituted phenyl wherein the alkoxy is of not more than four carbon atoms or halogenated phenyl wherein the halogen is bromine, fluorine or chlorine, R is phenylene, alkyl or alkoxy-substituted phenylene wherein the alkyl contains no more than four carbon atoms or halogenated phenylene wherein the halogen is fluorine, bromine or chlorine, and Y is selected from oxygen and sulfur but at least one of the Ys is sulfur and a is an integer having a value of l to 6 and a corrosion inhibiting amount of at least one triphenylborine of the formula wherein each of R, R and R are alkyl of not more than four carbon atoms, halogen (Cl, Br and F), alkoxy of not more than four carbon atoms, haloalkyl of not more than four carbon atoms and three halogen atoms (Cl, Br and F), haloalkoxy of not more than four carbon atoms and 3 halogen atoms (Cl, Br and F), phenOxy, phenylmercapto or- NO,, R, R and R are halogen (Cl, Br and F) or alkyl of not more than four carbon atoms, n, a and x are each integers of 0 to 3 and m, b and y are each integers of 0 to 2.

Representative groups for R, R and R in the above formula include halogen (Cl, Br and F), N0 phenoxy, thiophenoxy, alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl and t-butyl, alkoxy such as methoxy, ethoxy, butoxy, haloalkyl such as chloromethyl, bromomethyl, chloroethyl, bromoethyl, trichloromethyl, tribromomethyl, trifluoroethyl, dichloroethyl, chloro-n-propyl, bromo-n-propyl, bromo-nbutyl, bromo-tert-butyl, 1,3,3-trichlorobutyl and 1,3,3- tribromobutyl and haloalkoxy such as chloromethoxy, l,2dichlorobutoxy and fluoropropoxy. Representative groups for R, R and R include the halogen and alkyl listed above for R, R and R.

Representative boron compounds of the above formula include triphenylborine tri(3-methylphenyl)borine tri(4-n-butylphenyl)borine tri(2,4-dimethylphenyl)borine tri(4-methoxyphenyl)borine tri(4-chloromethylphenyl)borine tri( 3-fluoromethylphenyl )borine tri(4-trifluoromethylphenyl)borine tri(4-chlorophenyl)borine tri(2,4-dichlorophenyl)borine tri( 3-fluorophenyl )borine tri(4-phenoxyphenyl)borine tri(4-nitrophenyl)borine tri(4-phenylmercaptophenyl)borine tri(2-fluoro-4-methylphenyl)borine tri(2-methyl-4-chlorophenyl)borine tri(2-chloro-4-phenoxyphenyl)borine 2-methyl-3 '-methyl-4 -methyl triphenylborine 3 2-methyl-3'-fluoro-4"-fluorotriphenylborine The amount of boron compound employed in the compositions of this invention can range from about 0.01 to about 1.5 percent by weight. It is preferred to employ the acids in the compositions of this invention in amounts of from about 0.05 to about 1.5 percent by weight based upon the total composition.

The polyphenyl thioethers employed in the composition of this invention have from three to eight benzene rings and from one to seven sulfur atoms with the sulfur atoms joining the benzene rings in chains as ether linkages.

The term polyphenyl thioether as used herein means a compound or physical mixture of compounds wherein all of the Ys in the above formula are sulfur. The term "polyphenyl-ether-thioether" as used herein means compounds or physical mixtures of compounds wherein at least one but not all of the Ys in the above formula is sulfur.

The compositions of this invention contain a major amount of the polyphenyl thioether or polyphenylether-thioether base stock, i.e., at least 50 percent by weight of the total composition comprises an ether. It is preferred that at least 60 percent by weight of the composition be an ether base stock and even more preferred that at least 85 percent by weight of the total composition comprise an ether.

Illustrations of the alkyl-substituents present in the phenyl and phenylene groups of the ethers are for example, methyl, ethyl, propyl, butyl and the like. Illustrations of the alkoxy-substituents are, for example, methoxy, ethoxy, propoxy, butoxy and their isomers.

The compositions of this invention can also contain from 0.01 to percent by weight of the total composi: tion of a dialkyl hydrogen phosphite extreme pressure additive. The dialkyl hydrogen phosphites useful are those wherein the alkyl groups contain from one to 12 carbon atoms. The alkyl groups are for example, methyl, ethyl, propyl, isopropyl, ,butyl, sec-butyl, tbutyl, hexyl, decyl, isodecyl, dodecyl and the like.

Illustrative of the polyphenyl thioethers which can be employed as base stocks for the compositions of thisinvention are the bis(phenylmercapto)benzenes. For example m-bis(phenylmercapto )benzene o-bis(phenylmercapto)benzene p-bis(phenylmercapto)benzene bis(m-phenylmercaptophenyl)sulfide bis(o-phenylmercaptophenyl)sulfide bis(p-phenylmercaptophenyl)sulfide (m-phenylmercaptophenyl) (o-phenylmercaptophenyl)sulfide p-phenylmercapto-m'-phenylmercapto diphenyl sulfide o-bis(o-phenylmercaptophenylmercapto )benzene p-bis(p-phenylmercaptophenylmercapto)benzene p-bis(o-phenylmercaptophenylmercapto)benzene p-bis( n-phenylmercaptophenylmercapto )benzene m-bis(p-phenylmercaptophenylmercapto)benzene o-bis(p-phenylmercaptophenylmercapto)benzene and the like and mixtures thereof.

Illustrative of the mixed polyphenyl ether-thioether compounds which can be employed as base stocks in the compositions of this invention are for example,

o-phenylmercapto-m-phenoxy benzene p-phenylmercapto-o-phenoxy benzene m-phenoxy-p-phenylmercapto benzene o-phenylmercapto-p phenoxydiphenyl sulfide o-phenylmercapto-m phenoxydiphenyl sulfide o-phenoxy-m'-phenylmercaptodiphenyl sulfide m-phenoxy-p'-phenylmercaptodiphenyl sulfide o-phenoxy-p-phenylmercaptodiphenyl sulfide p-phenoxy-p-phenylmercaptodiphenyl sulfide o-phenoxy-o'-phenylmercaptodiphenyl sulfide o,o?-bis(phenylmercapto)diphenyl ether o-phenylmercapto-m-phenylmercaptodiphenyl ether o-phenylmercapto-p-phenylmercaptodiphenyl ether m-(m-phenylmercaptophenylmercapto) (mphenoxyphenylmercapto)benzene [m-( m-phenylmercaptophenylmercapto )phenyl [m- (m-phenoxyphenylmercapto)phenyljsulfide 3-(m-phenylmercaptophenylmercapto )-3 mphenylmercaptophenoxy)diphenyl sulfide 3,3-bis(m-phenylmercaptophenylmercapto)diphenyl ether 3-(m-phenylmercaptophenylmercapto)-3-(mphenoxyphenoxy)diphenyl sulfide 4-(m-phenylmercaptophenylmercapto )-4'-( mphenylmercaptophenoxy)diphenyl ether 3-( m-phenylmercaptophenylmercapto )-3 mphenoxyphenylmercapto)diphenyl ether 4,4'-bis(m-phenylmercaptophenoxy)diphenyl sulfide 4,4'-bis(m-phenox-yphenylmercapto)diphenyl sulfide 3-( m-phenoxyphenylmercapto )-3 mphenylmercapto phenoxy)diphenyl sulfide 3,3'-bis(m-phenylmercaptophenoxy)diphenyl ether 4-(m-phenylmercaptophenylmercapto )-4-(mphenoxyphenoxy)diphenyl ether 3-(p-phenylmercaptophenoxy)-3-(p-phenoxyphenoxy)diphenyl sulfide g3 m-phenylmercaptophenoxy )-3 mphenoxyphenylmercapto)diphenyl ether 3,3-bis(m-phenoxyphenylmercapto)diphenyl ether and 3-(m-phenoxyphenylmercapto)-3-(m-phenoxyphenoxy)-diphenyl sulfide In addition to the foregoing compounds, the phenyl and phenylene of such compounds can contain substituents, such as alkyl of one to four carbon atoms, alkoxy of one to four carbon atoms and halogen such as chlorine, bromine and fluorine. Examples of such compounds are as follows:

4,4'-bis(m-tolylmercapto)diphenyl ether 3,3'-bis(m-tolylmercapto)diphenyl ether 2,4-bis(m-tolylmercapto)diphenyl ether 3,4'-bis(m-tolylmercapto)diphenyl ether 3,3' bis(p-tolylmercapto)diphenyl ether 3 ,3 '-bis( xylylmercapto )diphenyl ether 4,4'-bis( xylylmercapto )diphenyl ether 3,4'-bis(xylylmercapto )diphenyl ether -3 ,4'-bis( m-isopropylphenylmercapto )diphenyl ether 3 ,3 -bis( m-isopropylphenylmercapto )diphenyl ether 2,4'-bis( m-isopropylphenylmercapto)diphenyl ether 3,4-bis(p-tert-butylphenylmercapto)diphenyl ether 4,4'-bis(p-tert-butylphenylmercapto)diphenyl ether 3,3'-bis(p-tert-butylphenylmercapto)diphenyl ether 3,3'-bis(2,4-di-tert-butylphenylmercapto)diphenyl ether 3 ,3 '-bis( 3-chlorophenylmercapto )diphenyl ether 4,4-bis(3-chlorophenylmercapto)diphenyl ether 3,3'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 4,4' bis(m-trifluoromethylphenylmercapto )diphenyl ether 3,4'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 2,3'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 3 ,3 '-bis( p-trifluoromethylphenylmercapto)diphenyl ether 3 ,3 '-bis( o-trifluoromethylphenylmercapto )diphenyl ether 3 ,3 '-bis(m-methoxyphenylmercapto )diphenyl ether 3,4-bis(m-isopropoxyphenylmercapto)diphenyl ether 3,4'-bis(m-perfluorobutylphenylmercapto)diphenyl ether 2-(m-tolyloxy)-2-phenylmercaptodiphenyl sulfide 2-( p-tolyloxy)-3'-phenylmercaptodiphenyl sulfide 2-(o-tolyloxy)-4-phenylmercaptodiphenyl sulfide 3-(m-tolyloxy)-3'-phenylmercaptodiphenyl sulfide 3-(m-tolyloxy)-4-phenylmercaptodiphenyl sulfide 4-(m-tolyloxy)-4-phenylmercaptodiphenyl sulfide 3-xylyloxy-4'-phenylmercaptodiphenyl sulfide 3-xylyloxy-3-phenylmercaptodiphenyl sulfide 3-phenoxy-3-(m-tolylmercapto)diphenyl sulfide 3-phenoxy-4'-(m-tolylmercapto)diphenyl sulfide 2-phenoxy-3 '-(p-tolylmercapto )diphenyl sulfide 3-phenoxy-4-(m-isopropylphenylmercapto)diphenyl sulfide 3 -phenoxy-3 m-isopropylphenylmercapto )diphenyl sulfide 3 -m-toloxy-3 m-isopropylphenylmercapto )diphenyl sulfide 4-(m-trifluoromethylphenoxy)-4'-phenylmercaptodiphenyl sulfide 3-(m-trifluoromethylphenoxy)-4-phenylmercaptodiphenyl sulfide 2-(m-trifluoromethylphenoxy)-3'-phenylmercaptodiphenyl sulfide 3-(m-trifluoromethylphenoxy)-3-phenylmercaptodiphenyl sulfide 3-(p-chlorophenoxy)-3-phenylmercaptodiphenyl sulfide 3-(m-bromophenoxy)-4'-phenylmercaptodiphenyl sulfide bis [m-(m-chlorophenoxy)phenyl]sulfide m-bis[3-(p-methylphenylmercapto)phenoxy[benzene m-bis[ 3-( m-trifluoromethylphenoxy )phenylmercapto]benzene m-bis[3-(m-bromophenoxy)phenylmercapto1benzene 3,3'-bis[m-(p-methylphenylmercapto)phenoxy]- diphenyl sulfide 3,4'-bis[m-(p-methylphenylmercapto)phenoxy]- diphenyl sulfide 3-(p-xenyloxy)-3'-phenylmercapto diphenyl sulfide, and the like and mixtures thereof. It is also contemplated within the scope of this invention to employ mixtures of polyphenyl ether-thioethers as base stocks.

The boron compounds useful in the compositions of this invention are well known to the art and can be prepared by reaction of phenyl lithium with boron halide as set forth in The Organic Chemistry of Boron, Acedemic Press, New York, 92, 93 (1961).

The following examples serve to further illustrate the I EXAMPLE meta-bis(phenylmercapto)benzene bis(m-phenoxyphenyl sulfide (m-phenoxyphenyl) (m-phenylmercaptophenyl)sulfide bis(m-phenylmercaptophenyl)sulfide 3 ring and 5 ring thioethers (50% by weight) (l2.5% by weight) (23.5% by weight) (12.65% by weight) (1.35% by weight) and containing 10 parts per million of a dimethyl silicone antifoam agent (Dow-Coming 200, 350 cs. fluid). After stirring at 40C. to dissolve the borine, the mixture is cooled to room temperature and filtered. A lubricant composition without a boron additive is used as control.

The useful life of a functional fluid can be determined on the basis of many criteria such as the extent of viscosity increase (oxidative stability) and corrosiveness toward metals under the conditions of use. The major bench scale method used for evaluating the oxidative stability of a functional fluid is the procedure given in Federal Test Specification 791, Method 5 308 according to which the lubricant composition is heated at a specified temperature in the presence of certain metals and oxygen and the viscosity increase of the lubricant is determined.

The compositions of this example are tested according to the procedure of Federal Test Specification 791, Method 5308, i.e., 500F. for 48 hours with 5 liters/- hour of air in the presence of steel, copper, silver, titanium, magnesium alloy and aluminum alloy. Information with respect to corrosiveness of the compositions to metals was also obtained. However, onlythe results upon copper and silver are reported since all the compositions tested had essentially no effect on the other metals employed. Viscosity measurements were made according to ASTM Method D-445-53T using a Cannon-Fenske modified Ostwald viscosimeter. The control base fluid ether and the composition of this invention exhibited substantially the same viscosity increase. The corrosiveness to metals was determined by weighing metal specimens of known size before and after the test. Results and further details are given in the Table below.

TABLE Metal Attack Boron Additive rug/cm Cu Ag None (control) 2.4 0.5 Triphenylborine 0.22 0.09

From the above it is clearly evident that the compositions of this invention exhibit markedly reduced corrosivity toward metals with no loss of oxidative stability and therefore have an extended useful life.

It will be appreciated that the compositions of the invention may also contain other additives, such as oxidation inhibitors, rust and corrosion inhibitors, antifoaming agents, detergents, viscosity index improvers such as polymeric materials for example, polyacrylate alkyl esters, polymethacrylate alkyl esters, polyoxyalkylene compounds, polyurethanes and the like. Such additives are usually employed in amounts as low as 10 parts per million for antifoaming agent to as much as 15 parts by weight of the total compositions for viscosity index im provers.

While this invention has been described with respect to specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

The embodiments in which an exclusive property or privilege is claimed are defined as follows:

1. Composition consisting essentially of a major amount of base fluid selected from the group consisting of polyphenyl thioethers, polyphenyl etherthioethers, and mixtures thereof having the formula wherein R is phenyl, alkyl-substituted phenyl wherein the alkyl is of not more than four carbon atoms, alkoxysubstituted phenyl wherein the alkoxy is of not more than 4 carbon atoms or halogenated phenyl wherein the halogen is bromine, fluorine or chlorine, R is phenylene, alkyl or alkoxy-substituted phenylene wherein the alkyl contains no more than four carbon atoms or halogenated phenylene wherein the halogen is fluorine, bromine or chlorine, and Y is selected from oxygen and sulfur but at least one of the Ys is sulfur and a is an integer having a value of l to 6 and a corrosion inhibiting amount of at least one triphenylborine of the formula wherein each of R, R and R are alkyl of not more than four carbon atoms, halogen selected from chlorine, bromine and fluorine, alkoxy of not more than four carbon atoms, haloalkyl of not more than four carbon atoms and three halogen atoms selected from chlorine, bromine and fluorine, haloalkoxy of not more than four carbon atoms and three halogen atoms selected from chlorine, bromine and fluorine, phenoxy, phenylmercapto or NO,, R, R and R" are halogen selected from chlorine, bromine and fluorine or alkyl of not more than four carbon atoms, n, a and x are each integers of O to 3 and m, b and y are each integers of 0 to 2.

2. Composition of claim 1 wherein the borine is present in an amount from about 0.01 percent to about 1.5 percent by weight based on the total composition.

3. Composition of claim 1 wherein the borine is triphenylborine.

4. Composition of claim 1 wherein m, b and y are zero.

5. Composition of claim 1 wherein m, b and y are zero and R, R and R are the same.

6. Composition of claim 1 wherein R is phenyl and R is phenylene.

7. Composition of claim 1 wherein n, a and x are zero and R, R and R are halogen.

8. Composition of claim 1 wherein m, b and y are zero and R, R and R are alkyl.

9. Composition of claim 8 wherein R, R and R are methyl.

l0. Composition of claim 8 wherein the borine is tri( 3-methylphenyl )borine.

l1. Composition of claim 8 wherein the borine is tri(4-methoxyphenyl)borine.

l2. Composition of claim 8 wherein the borine is tri(4-chlorophenyl)borine. 

2. Composition of claim 1 wherein the borine is present in an amount from about 0.01 percent to about 1.5 percent by weight based on the total composition.
 3. Composition of claim 1 wherein the borine is triphenylborine.
 4. Composition of claim 1 wherein m, b and y are zero.
 5. Composition of claim 1 wherein m, b and y are zero and R, R4 and R6 are the same.
 6. Composition of claim 1 wherein R2 is phenyl and R3 is phenylene.
 7. Composition of claim 1 wherein n, a and x are zero and R1, R5 and R7 are halogen.
 8. Composition of claim 1 wherein m, b and y are zero and R, R4 and R6 are alkyl.
 9. Composition of claim 8 wherein R, R4 and R6 are methyl.
 10. Composition of claim 8 wherein the borine is tri(3-methylphenyl)borine.
 11. Composition of claim 8 wherein the borine is tri(4-methoxyphenyl)borine.
 12. Composition of claim 8 wherein the borine is tri(4-chlorophenyl)borine. 